This invention relates generally to a method and apparatus for determining a value of torque at a desired location on a machine and, more particularly, to a method and apparatus for determining a value of torque as a function of the desired location and an operating condition relevant to the desired location.
It is often desired to know, during operation of a machine, how much torque is being applied to one or more locations on the machine. For example, a mobile machine having a drivetrain, e.g., an engine, torque converter, transmission, driveshaft, and axle shafts, generates torque all along the drivetrain during operation. The torque at these locations provides the power to perform the specific work functions demanded, but also create stresses on the components, thereby impacting the life of the various portions of the drivetrain.
It is therefore desired to have the ability to know how much torque is being applied throughout the operating life of the machine. Attempts have been made to use torque sensors, such as strain gauges and the like. However, the stress caused by the applied torque also causes stress-related problems with the sensors themselves, resulting in frequent inaccuracies and failure of the sensors. Furthermore, the required locations for the sensors often are in harsh environments. For example, a mobile machine such as an earthworking machine, e.g., wheel loader, truck, track-type tractor, agricultural machine, and the like, usually operates in harsh environments. Thus, the drivetrain of one of these machine, i.e., the location of any torque sensors used, is usually exposed to harsh operating conditions. The sensors, as a result, usually do not last very long.
Since the sensors themselves can be quite costly, the frequent loss of these sensors can be economically prohibitive.
Attempts have been made, with limited success, to determine the torque at a location based on data received from various parameters on the machine. For example, in U.S. Pat. No. 5,910,176, Creger discloses an apparatus and method for using a plurality of parameters associated with operation of an engine to determine a model of the torque being generated by the engine. However, a drivetrain has torque applied at many locations, and several of the locations would require a different approach for determining torque dependent upon an operating condition associated with that location. Since it is usually desired to know the value of torque being applied at many locations along a drivetrain, the operating condition must be known, and different sets of operating parameters must be chosen for each desired location.
Furthermore, since a drivetrain has a start location, e.g., an engine, and an end location, e.g., a set of axle shafts, it may be required to determine torque at each location from start to the desired location, since torque at the desired location is typically a function of torque at a preceding location. For example, to determine torque at the output of a transmission, it may be necessary to first determine torque at the output of a torque converter. Thus, an operating condition and a set of parameters may be needed to determine specifically the torque at the output of the torque converter, and another operating condition and another set of parameters may be needed to determine the torque at the output of the transmission.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention a method for determining a value of torque at a desired location on a machine is disclosed. The method includes the steps of choosing the desired location, determining an operating condition relevant to the desired location, determining a plurality of parameters of the machine, and determining a value of torque at the desired location as a function of the operating condition and the plurality of parameters.
In another aspect of the present invention a method for determining a value of torque at a desired location on a mobile machine is disclosed. The mobile machine has a drivetrain, the drivetrain including an engine, a torque converter, a transmission, at least one driveshaft, and at least one axle shaft. The method includes the steps of choosing a desired location on the drivetrain, determining an operating condition relevant to the desired location, determining a plurality of parameters of the mobile machine, and determining a value of torque at the desired location as a function of the operating condition and the plurality of parameters.
In another aspect of the present invention an apparatus for determining a value of torque at a desired location on a machine is disclosed. The apparatus includes a plurality of locations on the machine, means for determining an operating condition relevant to the desired location, means for determining a plurality of parameters of the machine, and processing means for determining the desired location, receiving information relevant to the operating condition at the desired location and the plurality of parameters, and determining a value of torque at the desired location using one of a neural network and an equation.
In another aspect of the present invention a method for estimating a value of torque at a desired location on a machine is disclosed. The method includes the steps of choosing the desired location, determining an operating condition relevant to the desired location, determining a plurality of parameters of the machine, and estimating a value of torque at the desired location as a function of the operating condition and the plurality of parameters, wherein the value of torque is estimated by one of an equation and a neural network chosen as a function of the desired location and the operating condition.
In another aspect of the present invention a method for determining a value of torque at a desired location on a machine is disclosed. The method includes the steps of choosing the desired location, determining a location preceding the desired location, determining a first operating condition relevant to the location preceding the desired location, determining a second operating condition relevant to the desired location, choosing a first plurality of parameters of the machine in response to the location preceding the desired location and the first operating condition, choosing a second plurality of parameters of the machine in response to the desired location and the second operating condition, determining a value of torque at the location preceding the desired location as a function of the first operating condition and the first plurality of parameters, and determining a value of torque at the desired location as a function of the determined value of torque at the location preceding the desired location, the second operating condition, and the second plurality of parameters.